Developmental plasticity among strains of the yellow mealworm, Tenebrio molitor L., under dry conditions

Edible insect production relies, among others, on the use of high-quality strains with good productivity characteristics. However, studies on the evaluation of the growth performance of different insect strains are limited. In this framework, the objective of the present study was to evaluate the growth and development under dry conditions of larvae of six Tenebrio molitor strains of different geographical origins, i.e. Greece, Italy, Turkey, Spain and USA, in terms of larval survival and development, as well as feed utilisation efficiency. In light of our results, we report the variable growth performance of different T. molitor strains in the absence of a moisture source. Although no significant differences were shown among the strains tested with regard to the final larval weights and survival rates, there were significant differences in the development time and the growth rate, which may affect the overall efficiency of T. molitor larvae production. Our study aims to highlight the significance of strain for the growth performance and consequently the productivity of T. molitor.

Fructose, glucose and fat interrelationships with metabolic pathway regulation and effects on the gut microbiota

The purpose of this 30-day feeding study was to elucidate the changes, correlations, and mechanisms caused by the replacement of the starch content of the AIN-93G diet (St) with glucose (G), fructose (F) or lard (L) in body and organ weights, metabolic changes and caecal microbiota composition in rats (Wistar, SPF). The body weight gain of rats on the F diet was 12% less (P = 0.12) than in the St group. Rats on the L diet consumed 18.6% less feed, 31% more energy and gained 58.4% more than the animals on the St diet, indicating that, in addition to higher energy intake, better feed utilisation is a key factor in the obesogenic effect of diets of high nutrient and energy density. The G, F and L diets significantly increased the lipid content of the liver (St: 7.01 ± 1.48; G: 14.53 ± 8.77; F: 16.73 ± 8.77; L: 19.86 ± 4.92% of DM), suggesting that lipid accumulation in the liver is not a fructose-specific process. Relative to the St control, specific glucose effects were the decreasing serum glucagon (–41%) concentrations and glucagon/leptin ratio and the increasing serum leptin concentrations (+26%); specific fructose effects were the increased weights of the kidney, spleen, epididymal fat and the decreased weight of retroperitoneal fat and the lower immune response, as well as the increased insulin (+26%), glucagon (+26%) and decreased leptin (–25%) levels. This suggests a mild insulin resistance and catabolic metabolism in F rats. Specific lard effects were the decreased insulin (–9.14%) and increased glucagon (+40.44%) and leptin (+44.92%) levels. Relative to St, all diets increased the operational taxonomic units of the phylum Bacteroidetes. G and L decreased, while F increased the proportion of Firmicutes. F and L diets decreased the proportions of Actinobacteria, Proteobacteria and Verrucomicrobia. Correlation and centrality analyses were conducted to ascertain the positive and negative correlations and relative weights of the 32 parameters studied in the metabolic network. These correlations and the underlying potential mechanisms are discussed.

Straw bedded pigsties height: Effect on growth and skin lesion of pigs

In order to ensure sustainable pig production in most tropical countries, alternative flooring systems need to be investigated and adopted. This five-week experiment was carried out to investigate the growth performance and skin lesion score of 36 weaned pigs raised on different heights of Guinea Grass Straw (GGS) beddings. The pigs were separated into four treatments in triplicate, in a completely randomized design. The treatments were: T1: 0m (concrete floor: without GGS), T2: 0.1m GGS, T3: 0.2m GGS and T4: 0.3m GGS. At the end of the experiment, data were collected on growth performance: final weight, weight gain, feed intake while feed conversion ratio (FCR) was calculated and skin lesions (front, middle and rear) measured. All data obtained were subjected to analysis of variance (ANOVA). Pigs on 0.2m had the highest (p<0.05) weight gain (4.75kg) compared with its counterparts on 0.1m (4.28kg), 0.3m (3.94kg) and T1(3.34kg). Final weight followed similar trend with pigs in 0.2m (9.94kg) having the highest weight compared with 0.1m (9.40kg), 0.3m (9.22kg) and T1 (8.55kg). The highest FCR (4.72) was recorded for pigs on 0m (control) which was an indication of poor feed utilisation while the least was with pigs on 0.2m (3.39). The result for skin lesion for the different parts revealed the least lesion occurred in pigs on 0.3m and higher occurrence in pigs on T1. Generally, skin lesions occur most at the front legs and heads. It can be concluded that the use of guinea grass straw at 0.1m and 0.2m height can improve the performance of weaned piglets while a height of 0.3m results in reduced skin lesions score. Afin d'assurer une production porcine durable dans la plupart des pays tropicaux, des systèmes de revêtement de sol alternatifs doivent être étudiés et adoptés. Cette expérience de cinq semaines a été réalisée pour étudier les performances de croissance et le taux de lésion cutanée de 36 porcs sevrés élevés sur différentes hauteurs de litières de paille de guinée (le 'GGS'- paille d'herbe de Guinée). Les porcs ont été séparés en quatre traitements en triple, dans une conception complètement aléatoire. Les traitements étaient: T1: 0 m (sol en béton: sans GGS), T2: 0,1 m'GGS', T3: 0,2 m'GGS' et T4: 0,3 m'GGS'. À la fin de l'expérience, des données ont été recueillies sur les performances de croissance: poids final, gain de poids, prise alimentaire tandis que le ratio de conversion alimentaire (FCR) a été calculé et les lésions cutanées (avant, milieu et arrière) mesurées. Toutes les données obtenues ont été soumises à une analyse de variance (ANOVA). Les porcs sur 0,2 m avaient le gain de poids le plus élevé (p <0,05) (4,75 kg) par rapport à leurs homologues de 0,1 m (4,28 kg), 0,3 m (3,94 kg) et T1 (3,34 kg). Le poids final a suivi une tendance similaire avec les porcs de 0,2 m (9,94 kg) ayant le poids le plus élevé par rapport à 0,1 m (9,40 kg), 0,3 m (9,22 kg) et T1 (8,55 kg). Le FCR le plus élevé (4,72) a été enregistré pour les porcs à 0 m (témoin), ce qui était une indication d'une mauvaise utilisation des aliments, tandis que le moins était pour les porcs à 0,2 m (3,39). Le résultat de la lésion cutanée pour les différentes parties a révélé que la moindre lésion était survenue chez les porcs à 0,3 m et plus chez les porcs en T1. En général, les lésions cutanées surviennent le plus au niveau des pattes avant et de la tête. On peut en conclure que l'utilisation de paille d'herbe de Guinée à 0,1 m et 0,2 m de hauteur peut améliorer les performances des porcelets sevrés tandis qu'une hauteur de 0,3 m entraîne une réduction du score des lésions cutanées.

Growth performance and feed utilisation in Clarias gariepinus fingerlings fed graded levels of melon (Citrillus lanatus) seed peel meal-supplemented die

A fifty-six (56) day experiment was conducted to evaluate the growth performance and feed utilization in Clarias gariepinus fingerlings fed with six iso-nitrogenous diets in which oven-dried melon (Citrillus lanatus) seed peel meal (MSPM) was substituted for yellow maize at 0, 20, 40, 60, 80 and 100% inclusion levels. A total of 270 fingerlings of C. gariepinus (mean weight: 7.40 ± 0.02 g) were randomly allocated into eighteen plastic bowls (50-litre capacity) at 15 fish per bowl and fed the control and experimental diets twice daily at 5% of their body weight. Proximate composition of melon seed peel meal-supplemented diets and fish carcass was determined using standard procedures. Results showed that crude protein was highest (60.75%) in fish fed diet 2 (20% MSPMsupplemented diet) and least (58.21%) in fish fed diet 4 (60% MSPM-supplemented diet). Fish fed diet 2 (20%MSPM-supplemented diet) had statistically (p < 0.05) superior values of MWG (48.27 g), SGR (1.56%/day) and FCR (0.48) beyond which growth and feed utilization indices gradually declined with increased level of MSPM inclusion. This study demonstrated that 20% substitution level of oven-dried melon seed peel meal produced the best growth and feed utilization in C. gariepinus. Keywords: Melon seed peel, Clarias gariepinus, Growth performance, Feed utilization

ESTIMATED DAILY METHIONINE + CYSTINE REQUIREMENTS OF BROILER CHICKEN

THE daily mthionine + cystine (MC) requirement of cobb-broiler chicken was estimated in three con­secutive experiments. In experiment 1, three groups of 30 day-old birds were fed one of eight diets. The diets contained bet­ween 0.52% and 1.08% MC in 0.08% stepwise in­crements. Liveweight gain peaked at 0.84% and 0.76% MC levels during 1-21 days (period 1) and 21-42 days (period 2) growth phases, respectively. MC intake/bird/d at these 0.84% and 0.76% MC levels was 0.21g and 0.42g respectively. Efficiency of feed utilisation was maximized at 0.76% MC level during each of the growth phases. In experiments 2, three groups (25/group) of 42-day old birds were fed one of eight diets. The diets contained between 0.48% and 1.04% MC in 0.08% stepwise increments. Liveweight gain and feed utilisation efficiency were maximized at 0.64% MC level during each of 42-63 days (period 3) and 63-84 days (period 4) growth phases. However, MC intake/bird/d was 0.58g during period 3 and 0.82g during period 4. Experiment 3 involved 9 diets ar­ranged in a 3 x 3 factorial design (Three energy levels: 2,800, 3,200 and 3,600 Kcal ME/kg diet; and three MC levels: 0.68%, 0.76% and 0.84). Each diet was fed to triplicate group of 30 day-old birds. The daily MC intake requirement of 1-28 day-old birds was 0.37g at 2,800 KcalME/kg diet; while that of 28-56 days old birds was 0.83 at 3,600 KcalME/kg diet.